Speaking of rodents, how is it that squirrels can eat the insulation off romex untill you're left with 3 bare pieces of copper? They don't die and must enjoy it because they continue to do it. I once opened a wall and found 6 feet of bare wire that was romex along with nesting material.
Re: grounding the switches--the center one looks grounded at least, can't see the ECG terminal on the others.
I've seen a mouse get into a light box with a porcelain keyless fixture somehow, and that was in Chicago with a conduit system. Zapped, burnt, and blowing out bulb after bulb till we checked it out.
I found a birds nest with newly hatched birds in a outdoor box--CBs and GFI receptacles at a campground. That actually happened a couple times, found numerous eggs, nests, etc. They came in through an open KO on the bottom. Actually I prefer an opening on the bottom to allow water to drain out, but not to let critters in. Wasp nests are the worst.
I found one of those things dead, with the tail end hanging out of the top of a trough that had a missing k/o, in a juice plant a few years back. I removed the cover and found the creature still had his jaws wrapped around a live 480 volt motor feed wire. YUCK!!!!!!